Wang Jin, Jing Ying, Song Lili, Xing Ying
LuoHe Medical College, Henan, China.
Department of Physiology, Medical College of Zhengzhou University, Zhengzhou, China.
Biochem Biophys Res Commun. 2016 Mar 18;471(4):628-32. doi: 10.1016/j.bbrc.2016.01.130. Epub 2016 Jan 22.
Alzheimer's disease (AD) is a progressive neurodegenerative disease, which is characterized by deposition of senile plaque (SP) and appearance of neurofibrillary tangles (NFT) in the cerebral cortex and hippocampus. SP is the accumulation of extracellular proteins/peptides, mainly consisting of the amyloid-beta protein (Aβ), and the atrophy-degraded neuritis, microglias and astrocytes. NFT could be induced by the abnormal phosphorylation of Tau protein. Aβ may interfere with certain cell signal systems, which affects the level of Tau protein phosphorylation thus resulting in the forming of NFT. The present study explored the role of Wnt/β-catenin pathway in the neurotoxic effect of Aβ25-35 on PC12 cells. Flow cytometry was employed to determine the effective sublethally dose of Aβ25-35, immunocytochemistry to decipher the intracellular distribution of microtubule associated protein-2 (MAP-2) and neurofilament H (NF-H), western blotting to assess the protein abundance of phosphorylated tau in several sites and GSK-3. As a result, the Polymerization of and MAP-2 and NF-H induced by Aβ25-35 could be significantly inhibited by Wnt3a(40 ng/ml), however enhanced by Dkk1(100 ng/ml). Meanwhile, the protein abundance of phosphorylated tau in several sites is decreased by Wnt3a, but increased by Dkk1 significantly compared with the control group. In conclusion, Wnt/β-catenin signaling pathway is involved in the neurotoxic effect of Aβ25-35 on PC12 cells.
阿尔茨海默病（AD）是一种进行性神经退行性疾病，其特征是大脑皮层和海马体中出现老年斑（SP）沉积和神经原纤维缠结（NFT）。SP是细胞外蛋白质/肽的积累，主要由β-淀粉样蛋白（Aβ）、萎缩降解的神经炎、小胶质细胞和星形胶质细胞组成。NFT可由Tau蛋白的异常磷酸化诱导。Aβ可能干扰某些细胞信号系统，影响Tau蛋白磷酸化水平，从而导致NFT的形成。本研究探讨了Wnt/β-连环蛋白通路在Aβ25-35对PC12细胞神经毒性作用中的作用。采用流式细胞术确定Aβ25-35的有效亚致死剂量，免疫细胞化学法分析微管相关蛋白-2（MAP-2）和神经丝H（NF-H）的细胞内分布，蛋白质印迹法评估多个位点磷酸化tau和糖原合成酶激酶-3（GSK-3）的蛋白丰度。结果显示，Wnt3a（40 ng/ml）可显著抑制Aβ25-35诱导的MAP-2和NF-H聚合，而Dkk1（100 ng/ml）则增强这种聚合。同时，Wnt3a可降低多个位点磷酸化tau的蛋白丰度，但与对照组相比，Dkk1可显著增加其蛋白丰度。综上所述，Wnt/β-连环蛋白信号通路参与了Aβ25-35对PC12细胞的神经毒性作用。
